Second Born Corrections to Wide-Angle High-Energy Electron Pair Production and Bremsstrahlung

Cross sections, correct to second order, are derived for the photoproduction of wide-angle electron pairs in a spherical, static nuclear charge distribution. For typical double-coincidence experiments it is found to be sufficient to treat only the convection current of the electron. The results obtained are essential to the interpretation of asymmetric electron pair production and may also be applied to wide-angle electron bremsstrahlung. For noncoincidence experiments in which one lepton is detected with most of the available energy, the higher Born corrections are shown to be identical with those of electron scattering. Numerical results are presented. The large asymmetries which have been reported for coincident pairs produced on a lead target are satisfactorily explained by the second Born contribution. The predicted asymmetry for pairs produced in carbon with invariant pair mass near the ${\rho }^0$ mass is small compared with the Compton contribution.